화학공학소재연구정보센터
Journal of Polymer Science Part A: Polymer Chemistry, Vol.50, No.2, 400-408, 2012
Synthesis of Thermo-Responsive Poly(N-vinylcaprolactam)-Containing Block Copolymers by Cobalt-Mediated Radical Polymerization
Thermo-responsive block copolymers based on poly(N-vinylcaprolactam) (PNVCL) have been prepared by cobalt-mediated radical polymerization (CMRP) for the first time. The homopolymerization of NVCL was controlled by bis(acetylacetonato) cobalt(II) and a molecular weight as high as 46,000 g/mol could be reached with a low polydispersity. The polymerization of NVCL was also initiated from a poly(vinyl acetate)-Co(acac)(2) (PVAc-Co(acac)(2)) macroinitiator to yield well-defined PVAc-b-PNVCL block copolymers with a low polydispersity (M(w)/M(n) = 1.1) up to high molecular weights (M(n) = 87,000 g/mol), which constitutes a significant improvement over other techniques. The amphiphilic PVAc-b-PNVCL copolymers were hydrolyzed into unprecedented double hydrophilic poly(vinyl alcohol)b-PNVCL (PVOH-b-PNVCL) copolymers and their temperature-dependent solution behavior was studied by turbidimetry and dynamic light scattering. Finally, the so-called cobalt-mediated radical coupling (CMRC) reaction was implemented to PVAc-b-PNVCL-Co(acac)(2) precursors to yield novel PVAc-b-PNVCL-b-PVAc symmetrical triblock copolymers. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 400-408, 2012